From this point to the Tambopata valley the road was unknown to my Indians, and had not been traversed since the time of the bark-trade, which came to an end fifteen years ago. It was supposed that any path which might once have existed would be entirely choked up by the forest, and I therefore started early in the morning, with Andres Vilca, to reconnoitre. The backbone of the ridge along which we travelled was not level, but up and down like a saw, and very rough work. After walking for a league the ridge ended where a transverse range of hills, at a lower elevation, connects the mountains on the further sides of the rivers of San Lorenzo and Laccani, and, closing up the ravines, contains their sources. This range, at right angles with the one over which we had journeyed, is called the _Marun-kunka_, and is covered with dense forests. It was necessary to force our way through this formidable obstruction, and we plunged into it at once. Our progress was vigorously opposed by closely matted fallen bamboos for the first few hundred yards, and afterwards we followed the course of a torrent, deeply cut in the rock, and forming a passage four to six feet deep, and about three feet across, with masses of ferns and the roots of enormous forest-trees interlacing across overhead, and two feet of exceedingly tenacious yellow mud underfoot. In many places it was almost dark at midday, while in others the rays of the sun succeeded in forcing their way through the ferns, and throwing a pale light across the otherwise gloomy passage. It was a weird unearthly scene. After several hours of very laborious travelling we at length forced our way across the Marun-kunka, and came out upon another _pajonal_, on the eastern side, whence there was a grand view of the forest scenery towards Tambopata, and the snowy peaks of the cordillera above Quiaca and Sina to the right.